Dizzy dos

Hi, my dad has been having symptoms of the feeling of passing out but doesn’t. His face drains in color & lips turn blue after 5 mins he’s ok but tired out. The doctors haven’t a clue what these episode’s are. He’s had a brain scan & is age 82. They have been on going for over a year and he can have from 1-8 aday.
He has lots of other symptoms but this seems to be a mystery to his gp Who is insisting this is anxiety& depression
Please can anyone throw any light on this